Nathan Woessner's parents told NBC's "Today" show their son has been getting up, moving around and even made a trip down the hall at Comer Children's Hospital on Sunday.

Child Pulled Out of Indiana Sinkhole Alive

A 6-year-old boy who spent more than three hours in an Indiana sinkhole was pulled out alive Friday evening. Emily Florez reports. (Published Friday, July 12, 2013)

“We’re just very, very grateful for everything they did for Nathan," his mother, Faith Woessner, said. “We can’t express our gratitude enough for the rescuers, and the nursing staff and everybody that’s helped bring Nathan back to us, and we’re thankful to God for being there with us and bringing Nathan back to us.”

Woessner fell into a sinkhole sometime after 4 p.m. July 12 at Mt. Baldy in Michigan City, Ind., and was buried under 11 feet of sand. It took 50 first responders to dig him out.

Grandfather Describes Boy's Fall Into Indiana Sinkhole

Nathan Woessner, 6, remains in critical condition after he fell into a sinkhole Friday at the Indiana Dunes. His grandfather, Don Reul, tells reporters about the boy's fall and rescue. (Published Monday, July 15, 2013)

Woessner's father, Greg, said he "just frantically wanted to get to him" and focus on his son kept him going.

"We are extremely thankful for not just his survival but everybody that had a role to play," Greg Woessner said, "and I can't say enough about everyone involved."

Woessner's grandfather, Pastor Don Reul, said the boy was walking to the top of the popular dune with his dad, an adult friend of the family and another boy when he fell.

"They immediately went back, and he was nowhere to be seen," Reul said. "The ground had swallowed him up."

Doctors said last Monday they expect the boy to be released from the hospital within 10 to 14 days. His condition had been listed as critical before Thursday.